This invention relates generally to pumping systems, and more specifically to such a system wherein a variable length pipe connects a pump-motor unit to a manifold unit. The manifold unit is connected by pipe to a dispenser located at a distance from the manifold unit. The pump-motor unit connected to a manifold unit is, for example, a submerged turbine pump (STP).
While the invention is described herein in connection with a gasoline pumping system of a service or filling station, it will be recognized that the invention may also have utility in other applications.
Gasoline service or filling stations commonly have underground storage tanks and above ground storage tanks for gasoline and a number of dispensing stands at the ground level. A pump-motor unit is mounted in each tank, and pipes connect each pump-motor unit to a manifold which is a small distance (7" to 70") above top of tank, the manifold being connected to the dispensing stands.
U.S. Pat. No. 3,172,567 and No. 3,197,085 to E. M. Deters et al. describe gasoline dispensing systems of the above nature.
A problem that is frequently encountered in the installation of such a system has to do with the pipes that connect the pump-motor unit to the manifold. It is common practice to provide two concentric pipes that suspend the pump-motor unit from the manifold which is above the tank. The inner of the two pipes house the power cable leading to the electric motor of the unit, and the annular space between the two pipes forms a flow conduit for gasoline flowing from the pump-motor unit to the manifold. The pipes support the pump-motor unit in the tank with the pump intake spaced about twelve centimeters above the bottom of the tank. The problem relates to the length of the pipe assembly necessary to properly locate the pump-motor unit. The length of the pipe assembly is dependent on a number of variables including the inside tank diameter, whether the tank is of steel or fiberglass, the tank bury depth, whether a sump adaptor is used and what its size is, whether a manway is used and its size, the horsepower rating of the pump-motor unit, and the manifold clearance. The information on all of these variables often is not available at the time an STP is ordered, and often the variables are changed during installation. As a consequence, it is often a misguided and dangerous situation to resize and machine the pipe assembly at the installation site, which increases the time and complexity of installation, and also voids approval listings (UL, CSA, etc.) and possibly warranty. This resizing creates a new assembly that has by-passed critical quality checks performed after assembly by the manufacturer.
It is a general object of the present invention to provide a variable length pipe assembly which is readily adjustable to different lengths and therefore avoids the foregoing problems.